The invention relates to a device for irradiating an object, with a transportable source which generates thermal neutrons and has a moderator, the neutron rays or beams arriving at the object through a collimator having at least one collimation duct or lane opening toward the object in funnel fashion.
Such a device is known from German Patent DE-PS No. 30 31 107. When examining certain objects such as control elements of boiling-water reactors, the irradiation time must occur within a given time frame in order to limit the disturbance of the cost-intensive operation of a nuclear reactor plant to a period which is only as long as is required for inspection work which is being simultaneously carried on. The source output of the conventional transportable neutron source is not to be increased, for weight, cost and safety reasons.